1. Field of the Invention
The present invention relates to a backlight device and a display apparatus having the same. More particularly, the present invention relates to a backlight device capable of controlling luminance of light emitted therefrom and a display apparatus having the backlight device.
2. Description of the Related Art
In general, a liquid crystal display (“LCD”) includes an LCD panel displaying an image and a backlight device supplying light to the LCD panel. The backlight assembly employs a cold cathode fluorescent lamp (“CCFL”) as its light source in one example.
An LCD may employ a dimming scheme controlling luminance of a backlight device for the purpose of increasing a contrast ratio of a display screen and reducing power consumption. The dimming scheme is classified into a pulse width modulation (PWM) control scheme and a tube current modulation scheme in one example.
In the PWM control scheme, a CCFL is repeatedly turned on and turned off in accordance with a duty ratio of a PWM signal. The PWM control scheme controls luminance of the backlight device by controlling on-off operation of the CCFL. On the other hand, the tube current modulation scheme varies the tube current of the CCFL by adjusting a level of a voltage applied to the CCFL, thereby controlling luminance of the backlight device. Since the tube current modulation scheme has a disadvantage of being difficult to control luminance in a low current, recently the PWM control scheme has been mainly used in an LCD rather than the tube current modulation scheme.
However, since the PWM control scheme controls the on-off operation of the CCFL, noise may disadvantageously occur due to coils in the inverter that repeatedly turns on and off the CCFL.